During engine operation, it is generally known to continuously control, by means of the engine control unit via regulator valve means in a conduit between the engine exhaust conduit and the engine intake conduit, the amount of recirculated exhaust in relation to the engine operating conditions, so that the best fuel consumption is maintained at the same time as response and low emission requirements are fulfilled. This controlling is, however, momentary and intrareferential, which means that it cannot predict and take into account transients in the engine operating state. Such transients are, for example, shifting in the vehicle gearbox or momentary throttle opening on an uphill incline after driving with torque reduction and engine braking in a downhill incline. When driving with exhaust recirculation, for example, smoke can appear from the engine exhaust pipe in connection with the torque reduction when shifting. Smoke is produced due to the fact that the closing of the recirculation valve initiated by the transient occurs so late that there is a volume of exhaust remaining in the intake manifold, which is drawn into the engine combustion chambers and results in increased particle emissions. This takes the form of smoke.